An elastic film for a hygiene articles can be made by premixing polymer components to make a polymer composite that contains styrene block copolymers and subsequently, by extrusion of the polymer composite, at least one layer is created, zeolites being added to the base compound and/or during extrusion.
For the production of elastic films, first a polymer composite is produced by a compounding process. The compounding process is a plastic-finishing process for targeted optimization of the product properties. In the production of elastic films, in particular in the hygiene sector, the polymer composite very often contains styrene block copolymers because of the favorable property profile and the relatively low costs. In the compounding process, polymer components are premixed with additives such as oil. This mixing is preferably performed in dual-screw extruders.
Due to the high thermal load during the compounding and extrusion process, styrene monomers are released in the case of polystyrene-containing formulations. These styrene monomers have a characteristic odor that is often perceived as being objectionable.
In EP 0 749 295 (US H1732), a hygiene article is described that comprises an upper layer that is permeable to liquids and a lower layer that is impermeable to liquids. An absorbing core is located between the two layers. The upper layer is a plastic film provided with openings and containing an amount of zeolite that has been impregnated with a heavy metal ion. The production article is suitable for minimizing odors that are caused by body fluids and sweat.
In U.S. Pat. No. 7,163,745, an odor-adsorption agent is described that is used in particular in the area of hygiene articles. The odor adsorption means comprises a granulate onto which subsequently, zeolites are molten.
A method with the characteristics of the generic claim of patent claim 1 is known from WO 2009/138887 and US 2009/0286444. Zeolites are cited in addition to a number of other organic and inorganic particles as possible filler substances. By means of the filler substances, the opacity of the film, or also the permeability of gas or steam is to be adjusted. For example, by stretching in the area of filler substances, pores can be created in order to provide a micro-porous, breathable elastic film.